Hi, I replaced my main halyard with 10mm braided polyester a while ago. The main reason was that the 8mm was slipping in the clutch (and yes I had to replace the clutch in the end!), but it was also reassuring to have something stronger. The main does not rattle down, so there may be a bit more friction, but it comes down with very little encouragement, .
I guess I am reassuring you that 10mm braided polyester is a practical alternative.
Bob S